Add stateful configuration

defaults/user-configuration/fhauser/applications/default.nix

@@ -20,7 +20,9 @@
     ./swaylock.nix
     ./kanshi.nix
   ];
-  home-manager.users.fhauser.home.packages = with pkgs;
+  home-manager.users.fhauser = {config, pkgs, ...}: {
+    home = {
+      packages = with pkgs;
         [ # Networking
           unison
           transmission # GUI Tools, maybe extract...
@@ -29,8 +31,6 @@
           chromium
           #midori  # TODO: Currently unused
           #qutebrowser  # TODO: Currently unused
-      gnome3.evolution # TODO: Suport for plugins with 21.05
-      #evolution-ews
           synergy
           #quicksynergy # Currently unused
           nextcloud-client
@@ -51,8 +51,8 @@
           #      gutenprintBin
           #      hplipWithPlugin
           simple-scan
-      gnome3.gnome-online-accounts
+          gnome.gnome-online-accounts
-      gnome3.gnome-control-center
+          gnome.gnome-control-center
         ] ++ [ # Communication
           signal-desktop
           tdesktop
@@ -73,5 +73,33 @@
           docker-compose
           vagrant
           virt-manager
+          modemmanager # TODO: makes sense here?
+          modem-manager-gui
         ];
+
+
+      #TODO: Write module
+      activation.statefulConfigSymlinks = config.lib.dag.entryAfter ["writeBoundary"] ''
+        set -eo pipefail
+
+        STATEFUL_CONFS=(
+          ".config/spotify"
+          ".mozilla"
+          ".password-store"
+        )
+        for STATEFUL_CONF in ''${STATEFUL_CONFS[@]}; do
+          if [ -e "$STATEFUL_CONF" ] && [ ! -h "$STATEFUL_CONF" ]; then
+            echo "File $STATEFUL_CONF already exists, exiting!" >&2
+            exit 1
+          fi
+
+          if [ -h "$STATEFUL_CONF" ]; then
+            rm "$STATEFUL_CONF"
+          fi
+
+          $DRY_RUN_CMD ln -s $VERBOSE_ARG "$HOME/.stateful/$STATEFUL_CONF" "$HOME/$STATEFUL_CONF"
+        done
+      '';
+    };
+  };
 }